Variations of soil lead in different land uses along the urbanization gradient in the Beijing metropolitan area.

Mao Q, Huang G, Ma K, Sun Z - Int J Environ Res Public Health (2014)

Bottom Line:
Few studies, however, have examined both factors together.Land-use types have an impact on soil Pb levels, however, when the degree of urbanization is considered, the impact from land use on soil Pb level was only significant in the transitional zone.Given the results of soil Pb in various land-use types, we suggest that future studies consider the urbanization gradient in which different land-use samples are located.

ABSTRACTUnderstanding the spatial pattern of soil lead (Pb) levels is essential to protecting human health. Most previous studies have examined soil Pb distributions by either urbanization gradient or land-use type. Few studies, however, have examined both factors together. It remains unclear whether the impacts of land use on soil Pb levels are consistent along the urbanization gradient. To fill this gap, we investigated variations in soil Pb level under different land-use types along the urbanization gradient in Beijing, China. We classified the degree of urbanization as the urban core, transitional zone, or suburban area and the land-use type as industrial area, roadside, residential area, institutional area, road greenbelt, park, or forest. Our results showed that the range of soil Pb levels in Beijing is <1 mg/kg-292 mg/kg, with a mean of 22 mg/kg. Along the urbanization gradient, the mean soil Pb level increased from the suburban area to the urban core. Land-use types have an impact on soil Pb levels, however, when the degree of urbanization is considered, the impact from land use on soil Pb level was only significant in the transitional zone. Parks and road greenbelts were found to have lower soil Pb, primarily due to soil restoration. Roadside and residential areas were found to have higher soil Pb because of traffic emissions, leaded paint, and previous industrial contamination. In the urban core and suburban area, the soil Pb level showed no significant differences among various land-use types. Given the results of soil Pb in various land-use types, we suggest that future studies consider the urbanization gradient in which different land-use samples are located.

Mentions:
To characterize the urbanization gradient, we sampled along eight transects from the city center to the suburban areas (east, southeast, south, southwest, west, northwest, north, and northeast) and established 78 survey plots at 3-km intervals along these transects, and we define the area within a 500-m radius as a plot. Next, we added 52 additional plots at 6-km intervals to capture the area between the eight transects in more detail. Our study includes 130 plots in total (Figure 1). We recorded the dominant land-use type at each plot. Within each land-use type, one composite surface soil sample (0–20 cm) was obtained by mixing three subsamples diagonally distributed within a representative 20 m × 20 m open space. A total of 451 soil samples were collected from July to September 2009.

Mentions:
To characterize the urbanization gradient, we sampled along eight transects from the city center to the suburban areas (east, southeast, south, southwest, west, northwest, north, and northeast) and established 78 survey plots at 3-km intervals along these transects, and we define the area within a 500-m radius as a plot. Next, we added 52 additional plots at 6-km intervals to capture the area between the eight transects in more detail. Our study includes 130 plots in total (Figure 1). We recorded the dominant land-use type at each plot. Within each land-use type, one composite surface soil sample (0–20 cm) was obtained by mixing three subsamples diagonally distributed within a representative 20 m × 20 m open space. A total of 451 soil samples were collected from July to September 2009.

Bottom Line:
Few studies, however, have examined both factors together.Land-use types have an impact on soil Pb levels, however, when the degree of urbanization is considered, the impact from land use on soil Pb level was only significant in the transitional zone.Given the results of soil Pb in various land-use types, we suggest that future studies consider the urbanization gradient in which different land-use samples are located.

ABSTRACTUnderstanding the spatial pattern of soil lead (Pb) levels is essential to protecting human health. Most previous studies have examined soil Pb distributions by either urbanization gradient or land-use type. Few studies, however, have examined both factors together. It remains unclear whether the impacts of land use on soil Pb levels are consistent along the urbanization gradient. To fill this gap, we investigated variations in soil Pb level under different land-use types along the urbanization gradient in Beijing, China. We classified the degree of urbanization as the urban core, transitional zone, or suburban area and the land-use type as industrial area, roadside, residential area, institutional area, road greenbelt, park, or forest. Our results showed that the range of soil Pb levels in Beijing is <1 mg/kg-292 mg/kg, with a mean of 22 mg/kg. Along the urbanization gradient, the mean soil Pb level increased from the suburban area to the urban core. Land-use types have an impact on soil Pb levels, however, when the degree of urbanization is considered, the impact from land use on soil Pb level was only significant in the transitional zone. Parks and road greenbelts were found to have lower soil Pb, primarily due to soil restoration. Roadside and residential areas were found to have higher soil Pb because of traffic emissions, leaded paint, and previous industrial contamination. In the urban core and suburban area, the soil Pb level showed no significant differences among various land-use types. Given the results of soil Pb in various land-use types, we suggest that future studies consider the urbanization gradient in which different land-use samples are located.